Fiber connections of the diencephalic nucleus tuberis anterior in the weakly electric fish,Gymnotus cf. carapo: An in vivo tract-tracing study

2007 ◽  
Vol 503 (5) ◽  
pp. 655-667 ◽  
Author(s):  
Ana Catarina Casari Giassi ◽  
Sonia Aparecida Lopes Corrêa ◽  
Anette Hoffmann
Keyword(s):  
Electric Fish ◽  
Weakly Electric Fish ◽  
Tract Tracing ◽  
Weakly Electric

scholarly journals Muscarinic Receptors Control Frequency Tuning Through the Downregulation of an A-Type Potassium Current

2007 ◽  
Vol 98 (3) ◽  
pp. 1526-1537 ◽  
Author(s):  
Lee D. Ellis ◽  
Rüdiger Krahe ◽  
Charles W. Bourque ◽  
Robert J. Dunn ◽  
Maurice J. Chacron
Keyword(s):  
Mathematical Modeling ◽  
Potassium Current ◽  
Electric Fish ◽  
Pyramidal Neurons ◽  
Frequency Tuning ◽  
Receptor Activation ◽  
Weakly Electric Fish ◽  
Weakly Electric

The functional role of cholinergic input in the modulation of sensory responses was studied using a combination of in vivo and in vitro electrophysiology supplemented by mathematical modeling. The electrosensory system of weakly electric fish recognizes different environmental stimuli by their unique alteration of a self-generated electric field. Variations in the patterns of stimuli are primarily distinguished based on their frequency. Pyramidal neurons in the electrosensory lateral line lobe (ELL) are often tuned to respond to specific input frequencies. Alterations in the tuning of the pyramidal neurons may allow weakly electric fish to preferentially select for certain stimuli. Here we show that muscarinic receptor activation in vivo enhances the excitability, burst firing, and subsequently the response of pyramidal cells to naturalistic sensory input. Through a combination of in vitro electrophysiology and mathematical modeling, we reveal that this enhanced excitability and bursting likely results from the down-regulation of an A-type potassium current. Further, we provide an explanation of the mechanism by which these currents can mediate frequency tuning.

scholarly journals The weakly electric fish, Apteronotus albifrons, actively avoids experimentally induced hypoxia

2021 ◽  
Author(s):  
Stefan Mucha ◽  
Lauren J. Chapman ◽  
Rüdiger Krahe
Keyword(s):  
Active Avoidance ◽  
Electric Fish ◽  
Electric Organ ◽  
The Other ◽  
Weakly Electric Fish ◽  
Dissolved Oxygen Concentration ◽  
Shuttle Box ◽  
Freshwater Habitats ◽  
Electric Organ Discharges ◽  
Weakly Electric

AbstractAnthropogenic environmental degradation has led to an increase in the frequency and prevalence of aquatic hypoxia (low dissolved oxygen concentration, DO), which may affect habitat quality for water-breathing fishes. The weakly electric black ghost knifefish, Apteronotus albifrons, is typically found in well-oxygenated freshwater habitats in South America. Using a shuttle-box design, we exposed juvenile A. albifrons to a stepwise decline in DO from normoxia (> 95% air saturation) to extreme hypoxia (10% air saturation) in one compartment and chronic normoxia in the other. On average, A. albifrons actively avoided the hypoxic compartment below 22% air saturation. Hypoxia avoidance was correlated with upregulated swimming activity. Following avoidance, fish regularly ventured back briefly into deep hypoxia. Hypoxia did not affect the frequency of their electric organ discharges. Our results show that A. albifrons is able to sense hypoxia at non-lethal levels and uses active avoidance to mitigate its adverse effects.

scholarly journals Electric signal synchronization as a behavioural strategy to generate social attention in small groups of mormyrid weakly electric fish and a mobile fish robot

2021 ◽  
Author(s):  
Martin Worm ◽  
Tim Landgraf ◽  
Gerhard von der Emde
Keyword(s):  
Small Groups ◽  
Electric Fish ◽  
Social Attention ◽  
Weakly Electric Fish ◽  
Electric Signal ◽  
Fish Robot ◽  
Wide Range ◽  
Signal Synchronization ◽  
Weakly Electric ◽  
Attention Hypothesis

AbstractAfrican weakly electric fish communicate at night by constantly emitting and perceiving brief electrical signals (electric organ discharges, EOD) at variable inter-discharge intervals (IDI). While the waveform of single EODs contains information about the sender’s identity, the variable IDI patterns convey information about its current motivational and behavioural state. Pairs of fish can synchronize their EODs to each other via echo responses, and we have previously formulated a ‘social attention hypothesis’ stating that fish use echo responses to address specific individuals and establish brief dyadic communication frameworks within a group. Here, we employed a mobile fish robot to investigate the behaviour of small groups of up to four Mormyrus rume and characterized the social situations during which synchronizations occurred. An EOD-emitting robot reliably evoked social following behaviour, which was strongest in smaller groups and declined with increasing group size. We did not find significant differences in motor behaviour of M. rume with either an interactive playback (echo response) or a random control playback by the robot. Still, the robot reliably elicited mutual synchronizations with other fish. Synchronizations mostly occurred during relatively close social interactions, usually when the fish that initiated synchronization approached either the robot or another fish from a distance. The results support our social attention hypothesis and suggest that electric signal synchronization might facilitate the exchange of social information during a wide range of social behaviours from aggressive territorial displays to shoaling and even cooperative hunting in some mormyrids.

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